Arrived on site to inspect water heater still giving error code. After speaking with Dave and showing him the price for a new igniter, they decided to let it run and see if they get the 8-4 flash error again. It has not happened since he hard reset the water heater yesterday. We watched the video he took of the error code and it definitely is an 8-4 flash which corresponds with a bad gas valve. There are no other causes of that error according to Rheem tech support. If he decides he wants the igniter, we have that and a spill switch on hand just in case.